1. Field of the Invention
The present invention relates to holographic memories where information is recorded by fixing the interference pattern of when the signal light and the reference light are internally interfered, and holographic recording apparatuses for recording information on the holographic memory, in particular, to the holographic recording apparatus suitably used in executing the precure process as the pre-process in recording.
2. Disclosure of Background Art
Generally, the holographic memory is recorded with information by fixing the interference pattern of when the signal light and the reference light are internally interfered to the holographic memory material layer. The signal light is spatially light modulated according to the recording information, and thus the interference pattern of light and dark corresponding to the recording information is produced at the holographic memory material layer when the signal light and the reference light are irradiated onto the holographic memory media. The refraction index distribution corresponding to the interference pattern is established in the holographic memory material layer when the monomer of high photo-polymerization in the holographic memory material layer is attracted and polymerized in the region of “light” of the relevant interference pattern. The recording of information on the holographic memory is thereby performed.
In the holographic memory, simultaneously recording a plurality of types of information on one recording location (recording block) by changing the incident angle of the reference light with respect to the holographic memory material layer (angle multiplexing) is known. That is, the interference pattern corresponding to the recording information can be fixed at the same recording location individually for every angle by spatially light modulating the signal light with different information for each incident angle of the reference light.
In recording of information, the precure process for activating the holographic memory material layer is performed as the pre-process. In the precure process, the light of waveband defined in advance is irradiated onto the recording position for a constant time. The energy of the light necessary for the precure process differs for each media. If the light is irradiated for longer than necessary in the precure process, the monomer in the holographic memory material layer is consumed, and the number of holograms that can be multiplexed on the recording layer reduces.